(1) Field of the Invention
This invention relates generally to communications and, more particularly, to wireless communications systems.
(2) Background Art
As used herein, the phrase “Wireless INfrastructure Network” or WINN refers to the wire-line portion of a wireless network that interconnects base transceiver stations (BTSs), mobile switching centers (MSCs), and base station controllers (BSCs), if any. The architectures of current WINNs have evolved from the AMPS (Advanced Mobile Phone Service) architecture which was formed two decades ago. The architecture considerations for these networks were driven by the need to interwork with the public switched telephone network (PSTN) and the requirements of voice services. For example, there is a hierarchical structure in which all traffic is routed first through an MSC to the PSTN.
It should be noted that although somewhat similar in hierarchical structure, each WINN is significantly different from the others. For example, each WINN supports a different wireless air interface technology, which couples the mobile units to the BTS. Examples of some wireless air interface technologies are: AMPS, CDMA (code division multiple access), GSM (Global System for Mobile Communications), and the proposed UMTS (Universal Mobile Telecommunications System). In addition, each WINN also has unique signaling protocols, e.g., between a base station and an MSC. Consequently, each WINN needs to be developed and maintained separately.
However, WINNs continue to evolve. Communication between an MSC and a BTS is evolving to a packet-based approach. For example, frame relay pipes can be used to transport voice and data traffic between an MSC and a BTS. Also, ATM (Asynchronous Transfer Mode) is being evaluated for use in transport of wireless traffic. Finally, there is Internet Protocol (IP) based transport (e.g., see the co-pending, commonly assigned, U.S. patent application of: Chuah et al, entitled “A Lightweight Internet Protocol Encapsulation (LIPE) Scheme For Multimedia Traffic Transport,” application Ser. No. 09/264,053, filed on Mar. 8, 1999.) However, within this evolution towards a packet-based approach, evidence of the AMPS architecture can still be found (e.g., a hierarchical structure in which all traffic is routed first through an MSC).